Machine for end grinding elongated workpieces



Feb- 26, 1952 G. F.V JOHNSON MACHINE FOR END GRINDING ELONGATED woRKPIEcEs Filed Feb. 2. 1949 n mi 1 fw@ Y@ Feb. 26, 1952 G. F. JOHNSON MACHINE FOR END GRINDING ELONGATED WORKPIECES 'Filed Feb. 2. 1949 5 Sheets-Sheet 2 d ttomegs wilg V Mdm Feb. 26, 1952 G. F. JOHNSON MACHINE FOR END GRINDING ELONGATED WORKPIECES 5 Sheets-Sheet 5 Filed Feb. 2, 1949 f ve ./ovfi- I 5 d Feb. 26, 1952 G. F. JOHNSON MACHINE FOR END GRINDING ELONGATED WORKPIECES 5 Sheets-Sheet 4 Filed Feb. 2. 1949 Feb. 26, 1952 G. F. JOHNSON MACHINE FOR END GRINDING ELONGATED woRKPIEc'Es 5 Sheets-Sheet 5 Filed Feb. 2. 1949 Patented Feb. 26, 1952 MACHINE FOR END GRINDING ELONGATED WORKPIECES Glen F. Johnson, Detroit, Mich., assignor to Bower Roller Bearing Company, Detroit, Mich., a corporation of Michigan Application February 2, 1949, Serial No. 74,197

17 Claims. `(Cl. 51-134) This invention relates to grinding machines and, in particular to machines and methods for grinding curved surfaces upon the ends of rotatable workpieces such as tapered bearing rolls and other elongated articles.

One object of this invention is to provide an improved automatic machine for grinding curved surfaces upon the ends of elongated rotatable workpieces such as bearing rollers or other elongated articles in a rapid and eicient manner.

Another object is to provide an improved automatic machine for grinding curved surfaces upon the ends of elongated rotatable workpieces wherein the end of the workpiece is ground by surface contact with the grinding wheel or tool rather than by line contactthereby producing a more accurate surface curvature in a shorter period of time.

Another object is to provide an improved automatic machine for grinding curved surfaces upon the ends of elongated rotatable workpieces wherein the workpiece holder and the grinding wheel are so constructed and arranged as to move the end of the workpiece and grinding wheel relatively to one another in a path lying between the axis of the grinding wheel and its periphery, thereby avoiding passing through the dead center of the wheel.

Another object is to provide an automatic machine for grinding curved surfaces on the ends of elongated rotatable Workpieces wherein each workpiece is urged against the lateral periphery of a driving wheel or disc by one or more pressure rollers or by a pressure roller cooperating with a contact finger, with the result that the workpiece is rapidly rotated as its end is drawn across the curved face of the grinding wheel to be ground.

Another object is to provide an automatic machine for grinding curved surfaces on the ends of elongated rotatable workpieces, of the foregoing character, wherein the pressure rollers are resiliently mounted either in Whole or in part so as to yieldingly urge the Workpieces against the driving wheel.

Another object is to provide an automatic machine of the foregoing character for grinding curved surfaces on the ends of elongated rotatable workpieces wherein the axes of the pressure rollers converge toward and are concentric with the axis of the rotary Workholder and preferably also the axis of the workpiece being ground, the surfaces of the pressure rollers being cylindrical, conical or barrel-shaped depending upon the arrangement and grinding conditions.

In the drawings:

Figure 1 is a side elevation, partly in vertical section, of a roller grinding machine according to one form of the invention, with the grinding Wheel and portions of the work holder broken away to disclose the internal construction;

Figure 2 is a top plan View, partly in approxiy mately horizontal section along the line 2--2 in Figure 1, of the roller grinding machine shown in Figure 1;

Figure 3 is an enlarged top plan view of a peripheral portion of the workpiece holder of the roller grinding machine shown in Figures 1 and 2;

Figure 4 is an enlarged vertical section along the line 4-4 in Figure 3;

Figure 5 is a vertical section along the line 5 5 in Figure 3;

Figure 6 is a top plan view of a bearing roller after being end ground by the roller grinding machine of this invention;

Figure 7 is an enlarged side elevation, partly in central vertical section, of a workpiece such as a bearing roller after end grinding by the machine shown in Figures 1 and 2;

Figure 8 is a fragmentary side elevation of a grinding machine having a modified work holder from that shown in Figure 1;

Figure 9 is a fragmentary end elevation of the portion of the grinding machine work holder shown in Figure 8;

Figure 10 is an approximately horizontal section along the line Ill-I0 in Figure 8;

Figure 11 is a fragmentary side elevation, partly in vertical section, of a grinding machine with a further modified Work holder;

Figure 12 is a fragmentary end elevation of the portion of the work holder shown in Figure 11;

Figure 13 is an approximately horizontal section along the line |3-l3 in Figure 11;

Figure 14 is a fragmentary side elevation of a grinding machine with a still further modified Work holder;

-Figure 15 is a fragmentary end elevation of the work holder shown in Figure 14;

Figure 16 is an approximately horizontal section along the line lB--IG in Figure 14;

Figure 17 is a fragmentary side elevation of a grinding machine with a still further modified work holder;

Figure 18 is a fragmentary end elevation of the work holder shown in Figure 17;

Figure 19 is an approximately horizontal section along the line |9-I9 in Figure 17;

Figure 20 is an approximately horizontal section thru a still further modified work holder fron that shown in the foregoing gures; and

Figure 21 is a diagrammatic elevational perspective View of the grinding wheel of the rollei` grinding machines of Figures l to 5 and 8 to 19 inclusive showing diagrammatically the path in which a workpiece is carried across the'face cf the grinding wheel by the work holder of the machine.

General construction In general, the grinding machine of this invention consists of a saucer-shaped grinding wheel which is rotated upon an .axis passing approximately through its center and against which the bearing rollers or other workpieces to be ground are brought by means ofa rotary work-holder of special construction and of which several modifications are described herein. Y general; however, the rotary work holder cons ists of a wheel-like or disc-like device having peripheral recessesinto which the workpieoes to be'fend groundare deposited one by one from a conventional feedingdeviceforming no part of the"pre sent ino/eiition.4 The work holder is rotat ablydriverrso as to carryY the endsofl the'workpieces `in an arcuate path across t-he curved surface of a grinding wheel which is being rotated orr'an' axis passing approximately through the center of the grinding surface of the wheel. The workpieces are forcibly rotated by the annular lateral peripheral surfaceV 'of a driving wheel whichislikewise power driven so as tobe forcibly rotated.

The workplaces' to be end ground are-forcibly urged against the driving wheel by one of several different forms-of pressure-applying mechanism. The irst form of the invention (Figures 1 -to i'inclu'sivel providesl av tapered pressure roller cooperating with` a contact finger having 'i tip of extremely hard-'wear-resisting material, such-fas tungstenY carbide or its equivalent, to crowdtheV workpiece against the driving wheel. A second forni (Figures 8 to 10 inclusive) provides a pair of tapered pressure rollers for each workpiece `wherein each pair of rollers is resilientlyxr'ioun'tedswith the axes of the rollers converging toward and coincident with' the axis of rotation ofthe carrier wheel. AA third form of the invention (Figures 11 to 13 inclusive) provides paired pressure rollers resiliently mounted on parallel axes; the'y rollersbeing tapered reversely, that is,` outwardly instead of inwardly. A fourthfo'rmof the invention (Figures 14 to 16 inclusive) providesl single fixed pressure rollers alternating with single resiliently mounted pressure'u'olle'rs with radial concentric axes, the' resilient rollers beingv convex'ed or of bulging shape. A' fifthforr'n of the invention (Figures 17 toV 19 inclusive) providespaire'd pressure rollers mountedon parallel axes, one roller of each pair being fixed vand the dthr being resiliently mounted, one of the rollers having a barrel-shaped form. Av sixthY form of the invention (Figure provides a rotary work holder wherein `the workpieces-'areY held against the lateral periphery of a rotary driving wheel by" a resiliently rirorne'd pressure'wheel or'disc, thereby causing the end ofy theworkpiece'to move across the concave face of a grinding wheel.

Grindingvunit and workpiece guides Referringeto the drawings in detail, Figures 1 to 5 inclusive show a grinding machine, generally; designatedr I0, consistingugenerally ofA a grinding unit, generally designated II, and a workpiece holding and driving unit, generally designated I2, both units being mounted upon a base or bed I3. The grinding unit II is common to all six forms of the invention, the dirierent machines varying in the workpiece holding and driving unit I2.Y The grinding unit II consists o a journal bearin'g'structure "I4 having a bearing housing I5 provided with'a dovetail slide I5 slidable to and fro in dovetail grooves I'I formed by spaced parallel guide bars I8 secured as at I9 to the machined'upper surface 25 of a boss 2l rising froriithe bed I3. Also mounted upon and secured to the upper surface 2B of the boss 2I are blocks 22 internally threaded as at 23 to receive adjusting screws 24; The inner ends of the adjusting screws 24 engage the opposite ends of the slideV I5 so that by tightening one screw and loosening the other, the slide IG and consequently the bearing housing I5 may be moved to and fro relatively to the guide bars I8 and locked in its adjusted position. Y

Rotatably lmcn'intedin suitable bearings (not shown) within the bearing housing I5 suchas by tainredv rllerbearingsv (not shown) isajshait 25. End plates 25 are rsecured tothe opposite ends 'ofthe bearinghousing It and acid the journai' bearing structur la in assembly.

Mounted on therearward end of the shaft 25 (Figure a) is a pulley 21 driven by s beit 2c from a pulley 29 rnounted upon the arinature shaft 30 of a motor SI. The latter is bolted tothe base I3. Mounted on the forward end of the shaft 25 is the hub 32 of a 1otay`disc or'fa-ceplate 33 which has al grinding wheel 34'secured Vto it, a disc 35 beinginteriiosedy between the grinding wheel 34 and the faceplate 33; The grinding wheel 34 itself consists of an approximatelycylim drical body 35 of abrasive material, such as silicon carbide or any other suitable-abrasive. The body 35 is' provided with aY `cent-ral recessv 31 and an annular concave grinding'surface 38 upon which the ends of the workpieces are grund as they pass across its face.

In order to guide .the ends of the workpiec's toward and away from the grinding surface 38 oi the grinding wheel 3rd, upper and lower workpiece guides 39 and 4i) respectively are provided, these having arcuate guide edges 4I and 42 of substantially the sameradius o l curvature as the grinding surface 33. The upper workpiece guide 39 is slotted as at 43 to receive fasteners 44 by which it` isl secured to the cross-bar of a TK-bracket 45 which, in turn, isv bolted asat 46 to a workpiece holder housing extension 4l (Figure 1). The housing extension 4l' projects upward from the workpiece holder housing 48 which, in turn, is ilanged as at 49 to rest upon and be secured to the machined upper surface 50 of an upwardlyextending boss 5I, as by the fasteners 52 (Figure 2)'. The boss 5I forms a part of the bed I3 and rises therefrom, approximately in the same level as the boss 2| supporting the grinding unit II.

AThe lower workpiece guide 4U is secured as at 53 to a projection 54 extending obliquely upward from a slide 55. The slide 55 is reciprocable in guideways 56 and has a longitudinal threaded bore 51 adapted to receive the correspondingly threaded end portion 58 of an adjusting shaft 59, the outer end of which is squared (not shown) or otherwise providedV with means for its rotation in order to move the slide 55 to and fro and thereby adjust the position of the workpiece guide d0. The interior of the slide 55 is hollowed out as at 60 beyond the threaded bore 51 in* order to facilitate the free rotation of the shaft 55.

The workpieces 6| (Figures 6 and 7) are show n, for purposes of illustration, as consisting of tapered anti-friction bearing rollers, the sides 62 of which are accurately conical and the upper end 63 is larger in diameter than the lower end 64. The upper end 63 is relieved by providing therein a recess 65 and this is surrounded by the annular ground area 66 produced by the action of the grinding wheel 34 and having a like radius of curvature R. The machine of the present invention, as previously stated, produces the annular curved surfaces 66 quickly and accurately by mass production methods.

workpiece feeding um't The workpieces, such as the tapered bearing rollers 6|, are fed to the workpiece holding and driving unit I2 by a workpiece feeding unit generally designated 61 shown at the upper left-hand corner of Figure 1. The workpiece feeding unit 61 forms no part of the present invention and any suitable feeding unit may be used, such as that shown in the co-pending application of Charles L. Hommel, Serial No. 597,389, led June 4, 1945, which issued as Patent No. 2,490,872 for Article Handling Apparatus. In this feeding unit 61, the -workpieces 6I are fed haphazardly from a hopper through selecting mechanism which insures that the workpieces drop with their small ends downward into a delivery tube 68, the lower end of which is mounted upon a bracket 69 bolted as at 'I0 to an arm 1| which, in turn, is bolted as at 12 to the housing 48. The arm 1| is preferably of angle cross-section with one of its flanges having spaced holes 13 for adjustably receiving the bolts in the location desired for the bracket 69 and delivery tube 68.

Workpzece holding and driving unit-first form The first form of the workpiece holding and driving unit I2 (Figures 1 to 5 inclusive) includes a driving assembly, generally designated 14, mounted in the housing 48 bolted as at 52 (Figure 2) to the boss 5| on the bed I3, as previously described. Mounted in the coaxial bores 15 in the housing 48 is a stationary shaft 16 held in position by a nut 11 threaded on the forward end thereof and rotatably supporting a gear 18. The gear 18 meshes with a gear 19 mounted upon and keyed as at 80 to a hollow shaft 8| rotatably mounted in coaxial bores 82 in the housing 48. A retaining ring or collar 83 threaded upon the rearward end of the hollow shaft 8| holds the gear 19 in assembly. The hollow shaft 8| is, in turn, provided with coaxial bores 84 which rotatably support a shaft 85 to the rearward end of which is keyed, as at 86, a gear 81 held thereon by a retaining collar 86 threaded upon the extreme rearward end of the shaft 85. The gear 81 is driven through reduction gearing (not shown) at a greatly reduced yspeed relatively to the hollow shaft 8|, such gearing being shown, for example, in the Johnson Patent 2,434,245, dated January 1'3, 1948, for Grinding Machine.

Bolted as at 90 to the head 9| on the forward end of the hollow shaft 8| (Figure 2) is a driving wheel 92 having an axially-projecting lateral annular portion 93 with a lateral tapered or inclined surface 94 corresponding to the taper of the sides 62 of the workpiece 6| (Figure 7). The surface 94 drivingly engages the workpieces 6| to rotate them while they are being held and moved downward across the grinding face 38 of the grinding wheel 34 by a workpiece holder generally designated 95.

The workpiece holder 95 is bolted as at 96 to a head 91 near the forward end of the shaft and has a supporting wheel or disc 98 provided with a bore 99 by which it is mounted on the extreme forward end portion |00 of the shaft 85 (Figure 2). Bolted as at I 0I to the rearward face |02 of the supporting wheel 98 is a workpiece holder or holding ring |03, the periphery of which is provided with spaced radial slots or notches |04 (Figures 1 and 3). The slots or notches |04 have circumferential widths slightly exceeding the widths of the workpieces 6I, the latter fitting loosely as they drop therein from the feeding tube 68 (Figure 1).

Bolted as at |95 to the forward face |06 of the supporting wheel 98 at circumferentiallyspaced intervals around the periphery thereof are radially-extending brackets |01. The outer ends of the brackets |01 are provided with lateral recesses |08 (Figures l and 3) in which axial arms |09 are bolted, as at III). The inner ends of the arms |09 are bent obliquely, as at I|I (Figure 3) and to the bent portions |I| are secured the supporting discs II2 of contact buttons I|3. The contact buttons ||3 are provided with convex contact surfaces ||4 (Figure 4) and are formed from extremely hard, wear-resisting material, such as tungsten carbide or the like. The button faces I|4 engage the sides 62 of the work-pieces 6| rearwardly of the centers of the notches |94 (Figure 3). The forward portions of their sides 62 are engaged by downwardly-tapered pressure rollers I I5 (Figure 3) rotatably mounted on headed notched pivot pins I I6 (Figure 2). The pins |I6 are inserted in slightly angled approximately radial bores ||1 in the peripheral edge or rim H8 of the supporting wheel 98, and are held in position'by set screws |I9 engaging the notched portions of the pins I9.

It will be seen from the dotted or chain lines indicating the various axes of rotation and alignment in Figures l and 2 that when the machine is properly designed and adjusted, the axis of rotation of the grinding wheel shaft 25 intersects the common axis of rotation of the shafts 8| and 85 at a common point P. It will also be seen that the axes of the pivot pins I|6 and therefore the axes of rotation of the pressure rollers I|5 also intersect at this same common point P. Moreover, the tapered surface of each pressure roller ||5 coincides with the surface of a cone, the apex of which lies at the point P. Furthermore, the center of curvature of the grinding surface 38 of the grinding wheel 34 also coincides with the point P when the machine is properly adjusted. Finally, the axes of rotation of the workpieces 6| intersect the point P and the shallow cone which forms a continuation of the annular driving surface 94 of the driving wheel 92 (Figure 2)A likewise passes through the point P. The dimensions of the machine are also preferably chosen so that the sides 62 of the workpieces 6| (Figure 2) coincide with the surface of a cone, the apex of which is located at the point P.

Operation of first form of machine In the operation of the rst form I0 of the grinding machine of this invention, semi-finished workpieces 6I are placed in the receiving hopper (not shown) of the feeding unit 61 at the upper left-hand corner of Figure l, these workpieces having comparatively flat larger ends. The selector mechanism of the feeding unit 61, as previously stated, tilts the workpieces one Way or the other so that they all descend through the feeding tube 69 with their smaller ends downward, regardless of the haphazard manner in which they were placedA in the hopper. The workpieces 3i with their smaller ends downward, drop into the notches Hifi of the workpiece holder |03 which meanwhile is rotating slowly in a clockwise direction toward the grinding wheel 34 while the driving wheel 92 is more rapidly rotating in the same direction. At the same time, the workpieces 3| are engagedv by the contact buttons |3 (Figure 3) and pressure rollers HE at locations spaced approximately 90 degrees from one another, these elements cooperating to crowd the workpieces 6| against the driving surface 94 of the driving wheel 32. As a consequence, the workpieces 6| are rotated rapidly around their axes while they are conveyed in a circular path, a portion of which crosses the grinding surface 38 of the grinding wheel 34 as shown by the successive dotted ovals and circles in Figure 2l.

As the wcrkpieces 8| move downward toward the grinding wheel 34 (Figure l) they are retained in the notches |84 by the arcuate guiring edge il of the upper workpiece guide 39. They are also urged radially outward by the contact of their tapered surfaces 32 with the oppositely tapered conical surfaces of the driving wheel surface 9i and pressure rollers H. In this manner the ends 63 of the workpieces are brought into engagement with the grinding wheel surface 38 so that their portions 3.a are ground to the desired curvatures with the radius R.

In the meantime, the motor 3| (Figure 2) has been driving the shaft 25 to rotate the grinding wheel 34, the grinding surface 38 of which has previously been provided with the curvature desired for the curved end surface 66 upon the l.

workpieces 6|, this curvature having the radius R shown in Figure 7. The surface 38 is maintained at this curvature by a conventional grinding wheel truing 'or dressing device (not shown) of any one of several types well known in the grinding art. As the larger ends of the rotating workpieces are carried downward over the grinding surface 38 of the grinding wheel 34, they are ground to the curvature thereof.

Immediately after the workpieces 6| emerge below the grinding wheel 34 (Figure 1), they are engaged by the arcuate guiding edge of the lower workpiece guide 4U, which has previously been adjusted to the correct position by rotating the screw shaft 59. When the workpieces 6| pass beyond the guide 49 they drop out of the notches |84, as shown at the bottom of Figure 1, and pass int-o a suitable receiver. Thus, the contact buttons ||3 on the ends of the arms |39 (Figure 3) cooperate with` the pressure rollers H5 to automatically urge or crowd the workpieces 6| against the driving wheel 92 regardless of minor variations in the diameters of the workpieces 6| arising during manufacture.

workpiece holding and driving unit-second form' The second form of workpiece holding and driving unit generally designated |20 (Figures 8 to 10 inclusive) includes a driving assembly generally designated |2| similar in construction and operation to the driving assembly 14 of Figures 1 to 5 inclusive and having corresponding parts similarly designated. The workpiece holder, generally designated |22, is similarly bolted as at 96 to the` head 31 yor annular flange on the innerfshaft 85, but is itself of modiedv design.

The workpiece holder or holding ring |83 is-also similarly bolted as at IUI to the rearward face |02 of the supporting wheel 98 and is similarly provided with spaced workpiece receiving slots or notches |84. In the modification shown in Figures 8 to 10 inclusive, however, constituting the second form of the invention, the workpiece 6| is held against the driving wheel 92 by apair of resiliently mounted rollers rather than by the cooperating roller and finger of Figures 1 to 5 inclusive.

In particular, the supporting wheel or disc 98 has bolted thereto as at |23 (Figure 8) a series of paired right-hand and left-hand brackets |24 and |25 respectively of trowel-shaped form having sockets |26 for receiving pivot pins Piv-otally mounted between each` pair of brackets |24, |25 is an arm |28 having a recess |29` near the inner end thereof (Figure 10) adaptedV to receive the pivot pin |21. The periphery of 'the supporting wheel 88 is provided with threaded bores |30 in which are mounted studs |3| passing through enlarged holes |32 in the arms |28 and carrying compression springs |33 compressed against the arms |28 by nuts |34.

TheY arms |28 are of roughly T-shaped form with spaced pairs of radially-directed sockets |35 in the cross portion thereof. Secured as at |33 in the sockets |35 are headed pivot pins |37 rotatably supporting inwardly-tapered pressure rollers |38. As was the case with the first form of the invention, the point P on the axis of rotation of the shafts and 8| is the common point of coincidence of the axis of rotation of the grinding wheel 34, the center of curvature of its grinding surface 38, the point of intersection of the conical surface 34 on the driving wheel 92, the axes of rotation of the workpieces 5| and pressure rollers |38, and the location of the apex of the cone which coincides with the tapered surface of the workpieces 6| and also of the pressure rollers |38.

The operation of the second form of the invention shown in Figures 8, 9 and 10 is similar to that of the first form, except that the workpieces 6| are urged against the driving surface 94 of the driving Wheel 92 by the resiliently mounted pressure rollers |38, as governed by the pressure of the springs |33. The pressure of the springs |33, in turn, can be varied by screwing the nuts |34 inward or outward along the threaded portions of the studs |3|. As the pressure rollers |38 rotate in response to the rotation of the workpieces 6|, they cooperate with the conical driving surface 94 on the driving wheel 82 to urge the workpieces 6| radially outward against the grinding surface 38 of the grinding wheel 24, by which their end portions 66 acquire the desired curvature of radius R. The remainder of the operation of the second form of the invention is otherwise substantially the same as that of the first form previously described.

Workpiece holding and driving unit-third form The workpiece holding and driving unit, generally designated |48 of Figures ll, 12 and 13 has a cl-ose similarity with the second form of Figures 8, 9 and 10 and similar parts are similarly designated. In Figure 11, however, the pivot pin holes |4| in the cross bar of the. T- shaped arms |28 are parallel in each pair rather than converging toward the point P as in the case of the bores or sockets |35 in Figure 8. The pressure rollers |42 are also heldin, place by headed pivot pins |43 seated in the bores |4| and secured by grooves |44, but the pressure rollers |42 are tapered outward rather than inward.

The Ioperation of the third form of the invention is substantially the same as that of the second form shown in Figures 8, 9 and 10, except that the work pieces 6| are urged outward against the grinding wheel 34 by the cooperation of the outwardly-tapered conical rollers |42 on parallel axes of rotation and the conical driving surface 94 on the driving wheel 92. The operation is otherwise similar to that of the second form of the invention in Figures 8 to 10 inclusive.

Workpiece holding and driving unit-fourth lform The fourth form of workpiece holding and driving unit, generally designated |50 shown in Figures 14, 15 and 16 is in many respects similar to that of the first form shown in Figures 1 to 5 inclusive, and similar parts are similarly designated. The iixed pressure rollers are mounted on headed pins |52 secured in radially directed sockets |53 by screws |54. Instead of .the contact fingers |89, the fourth form |50 makes use of convex or bowl-shaped resilientlymounted pressure rollers |55 rotatably mounted upon pivot pins |56 secured in a bore |51 in an L-shaped arm |58 having a slot |59 for receiving the pressure roller. The inner end of the L- shaped arm |58 carries a pivot member |60 seated in a socket |6| (Figure 16) by which the arm |58 is given some freedom of motion and adjustment. The arm |58 is held against the supporting wheel 98 by a stud |62 threaded into a bore |63 therein. The stud |62 passes loosely through an enlarged bore |64 and carries a compression spring |65 which is compressed by a nut |66 threaded on the outer end of the stud |62. The upper or outer end of the arm |58 is provided with a projecting portion |61 which extends between adjacent workpieces 6| and is suitably concave as at |68 on its opposite edges to provide clearance for the workpieces 6| (Figure 15). The fixed rollers |5| and the resiliently vmounted rollers |55 alternate in succession around the periphery of the supporting wheel 98, the pressure rollers |55 being urged toward the driving surface 94 of the driving wheel 92 by the coil springs |65.

The geometrical relationships of the various surfaces and axes of rotation in the fourth form of the invention shown in Figures 14, 15 and 16 are similar to those previously described in connection with the second form of theinvention shown in Figures 8, 9 and 10, except that, of

course, the pressure rollers |55 do not have coni-- cal tapered surfaces. In other respects, however, the point P on the axis of rotation of the shafts 8| and 85 is not only the center of curvature of the grinding surface 38 of the grinding Wheel 34, but is also the point of intersection of the axis of rotation of the grinding wheel 34 and of the rollers |5| and |55 as well as being the apex of cones coinciding with the driving surface 94 and the fixed rollers |5|.

The operation of the fourth form of the invention is similar to that of the other forms of the invention previously described except that the bulging or convexed surfaces of the resiliently-mounted rollers |55 do not, of course, engage the workpieces 6| except in a point contact at any one time, Whereas the tapered contact rollers |58 of Figure 8 and I5 of Figure 1 engage the workpieces 6| in a line contact. In this rspect, the rollers |55 are somewhat analogous to the pressure or contact buttons ||3 of Figure 3. The operation of the fourth form |50 is otherwise substantially the same as the operation of the previously-described forms of the invention, and hence requires no repetition.

Workpiece holding and driving unit-fifth form The workpiece holding and driving unit, genon each pivot pin |19 is a swinging arm |80` which, on its outer end, is provided with a bore parallel to the bore |13 when the two are adjusted to lie side by side. Secured as at |82 in the bore |8| is a headed pivot pin |83 on which is mounted a convex approximately barrelshaped pressure roller |84 (Figure 17). Intermediate its opposite ends the arm |80 is provided with a bore |85 through which passes a stud |86, the inner end of the latter being threaded into a bore |81 in the supporting wheel 98 (Figure 19). The bore |85 is considerably larger in diameter than the stud |86 so as to permit free tilting movement therebetween without interference. A coil spring |88 surrounding the stud |86 and held in position by an adjusting nut |89 threaded on the outer end of the stud |86 urges the arm |80 and hence the pressure roller |84 into engagement with the workpiece 6| and urges the latter into driving engagement with the driving surface 94 of the driving wheel 92. A set screw |90 threaded into the threaded bore |9| limits the extent of swing of the arm |80 (Figure 19) by engaging the forward face |06 of the supporting wheel 98.

The geometrical relationships of the various axes and centers of curvature of the fifth form |10'of Figures 17, 18 and 19 are generally the same as in the third form of Figures 11, 12 and 13. The center of curvature of the grinding surface 38 lies on the axis of rotation of the shafts 8| and 85 at the point P which is also the point of intersection with the axis of rotation of the grinding wheel 34 with that of the shaft 85. The conical surfaces coinciding with the driving surface 94 of the driving wheel 92 and the side surfaces 62 of the workpieces 6| have their apices located at the point P. The axes of rotation of the pressure rollers |16 and |84, however, being parallel to one another, doV not intersect at the point P.

The operation of the fifth form of workpiece holding and driving unit |10 is generally similar to that of the third form shown in Figures 11 to 13 inclusive except that one of the pressure rollers of each pair is iixed and one is resiliently mounted. Consequently, the rollers |16 and 84 urge the tapered workpieces'l into contact with Y the driving surface 94 and also urge them radial- 'assegics 11 The'remainderof the operation is substantially as 'that described inconnection with the foregoing forms of the invention and hence requires noV repetition.

workpiece holding and driving unitsixth form The sixth form of workpiece holding and driving unit, generally designated 200 shown in Figure 20 differs considerably from the forms previously described although it is similar as regards the construction of the driving wheel 92 andY work holder supporting wheel 98. Similar parts `are similarlyV designated. The wheel 98 has the 'notches |011 'directly in its periphery rather than in a separate annular plate, as in e y path downward across the grinding face 38 of 'the grinding wheel 35, At the same time, the pressure wheel 203 rotates as'an idler with its resilient rim 20! urging the Workpieces 6| against the driving surface 94. At the'lsame time, due to the fact that the space between the inner surface Vof 'the pressure plate 20| and the `driving surface 94 is flared or divergent in the direction of the grinding wheel`34, the workpieces BI are likewise urgedradially outward in their notches |04 against the grinding surface 38 and also against the arcuate edges 4I and 42 (Figure 1) of the workpiece guides 39 and 40. In the siXth form of the invention (Figure 20), the end of the workpiece 6I has surface contact with the grinding wheel surface 38 as it moves across the latter, rather than line contact asin the applicants prior Patent No. 2,434,245 of January 13, 1948 previously referred to. Thissurfacegrinding action gives a' surface of improved 12 4quality on theend "portions-'166 of the workpieces' 6i as compared with -the-line contact* grinding given by the-machine-of the applicants aforesaid patent.

What Iclaim is:

1. -A machine for -end grindingel'ongatedworkpieces comprisingv a v rotary grinder having -a grinding surface thereon,=a rotary workpiece holder having a periphery Vthinner than said workpieces mounted for motion of said periphery inclcselproximity to -said grinding surfacasaid periphery having A therein workpiece-holding recessesopen laterally toA expose the sides of said work-pieces, a, Yrotary* driving element engageable with said workpieces on one side of said workthe preceding' OIIIIS 0i the invention Pressure 10 piece holder, and a rotary pressure device having iS'apDlied t0 the WOIkDieCeS 6| t0 Urge them into pressure rollers engageable with said Workpieces engagement with the driving 'Surface 94 0f the on the opposite side of said workpiece holder to 'driving' Wheel 92 "by a fleXible Spring plaie 20| urge said workpieces into driving engagement of 'annular form secured as at 202 toa pressure '20 With'said'di-iving element, Wheel The latter iS Secured as at t machine for elongated wvorkafheador flange 205 on a shaft 206. The shaft pieces Comprising a rotary grinder having a -205 'iS 'molliliedin Suitable bearings 207 in a# grinding surface thereon, a rotary workpiece heilSiIlg '203 Which il! tum i5 mounted 0n the bed holder having a periphery thinner than said worki3` (not shown). The shaft 206 and Aconsequent- 25 pieces mounted for motion ofsaid periphery in vly the pressure wheel 203 and pressure plate 201 close proximity to Said grinding Surface, Said rotate freely and are not power-driven like the periphery having therein workpiecedioiding re- Shafts 8| and 35 WliiCh diiVe ille driving Wheel cesses open laterally to expose the sides of said '92 and workholder and supporting wheel 98. The workpieces, a, roi-,ery driving element engageable grinding Wheel 34 With its grinding Surface 3S y30 With'said workpieces on one side'ofsaid workpiece is substantially the same as that described in home?y and-a rotary pressure device having pres- Figure 1J and iS Similarly 'mounted and di'iVeiisure rollers engageablewith said workpieces on The hOuSiIlg 208 iS mOilIli'eCl S0 that its axis 0f the opposite side of said workpiece holder to uree `rotation. may lbe SO as to Crowd the said workpeces driving engagement, rif/h pressure pleteiil against the WOlkDiGCeS in `35 saidedriving element,certain of said rollers being order to urge them against the driving surface resiiiehtiy-modnted 0h Said device, 94 of the driving wheel 92and likewise urge the -3 A machine for end grinding elongated'workends `B3 of the workpieces `6I outward against pieces comprising a Tot-.ary grinder having a the grinding Surface 33- grinding surface thereon, a vrotary workpiece The geOmei'ICal lelaiiOIlShiDS eXiStiIlg in the 40 holder havingaperiphery thinner thansaid worksixth form of the invention shown in Figure pieces mounted for motion efsaid periphery in 'are similar in a few respects to those existing close proximity i0 Said grinding Surface, said in the 'previously described forms of the invenperiphery having therein workpiece h01dihg re 'tion in that the AAaxis "of rotation of the grinding casses open laterally t0-expose `the Sides 0f seid wheel 34 intersects the axis of rotation at a comi 45 worhpieees, a, roi-,ery driving element engageable men-point P which'is also the center of curvawith said workpieces'on one side of 4said workture of the grinding surface 38 and likewise the piece holderrahda-fotary pressure device having 'apeXOf the 00D@ fOimeOl by the Side Surface 52 pressure rollers/and Ypressure fingers engageable Of the 'WOIkpieCe 5L with said workpieces `on the opposite side of said 111 theepeieiion 0f i'Ille SiXill Oim 0f the in' 150 workpiece holder to urge Ysaid worlfzpieces into Veniienfiiie Shafts 3i and 35 are' loilaiiedfas be driving engagement with said driving-element. fore, at diiei'ent SpeedS, the driving Wheel '92 4.-A'machine for-'end grinding elongatedwork- Ietatillg more rapidly than the SIlDDOiiing Wheel pieces comprising -a rotary grinder having a This action, as before, rotates the workpieces 6l grinding Surface thereon `a 'rotary workpieee and at the Sametime, carries them in an arcuate 455 holder having aperiphery `thinner than saidworkpieces mounted for 'motion of said periphery in close proximity to said grinding surface, said periphery having therein workpiece-holding frecesses'open ylaterally to expose 'the sides of said 160 Workpieces, arotary driving elernenthengageable with said workpieces -cnf one `side of said workpiece holder, and a rotary Ypressure vdevicehaving pressure rollers engageable with said workpieces on the opposite side of said workpiece holder to urge said workpieces'into driving engagement with said driving element, certain of lsaid rollers being xedly mounted and others 'of said rollers being resiliently mounted-on said' device.

5. A machine for end grinding'elongated workpieces comprising` a rotary grinder having a grinding `surface thereon, a rotary workpiece holder having aperiphery thinner than vsaid work- 'pieces mounted vfor'motion of said periphery in close proximity Vto `said vgrinding* surface, said 'peripheryiha'ving therein-#workpieceholding vreassacse cesses open laterally to expose the sides of said workpieces, a rotary driving element engageable with said workpieces on one side of said workpiece holder, and a rotary pressure device having pressure rollers engageable with said workpieces on the opposite side of said workpiece holder to urge said workpieces into driving engagement with said driving element, the axes of rotation of said pressure rollers being directed through a substantially common point of intersection on the axis of rotation of said driving element.

6. A machine for end grinding elongated workpieces comprising a rotary grinder having a grinding surface thereon, a rotary workpiece holder having a periphery thinner than said workpieces mounted for motion of said periphery in close proximity to said grinding surface, said periphery having therein workpiece-holding recesses open laterally to expose the sides of said workpieces, a rotary driving element engageable with said workpieces on one side of said workpiece holder, and a rotary pressure device having pressure rollers engageable with said workpieces on the opposite side of said workpiece holder to urge said workpieces into driving engagement with said driving element, said rollers being mounted in pairs on said device with the rollers of each pair having substantially parallel axes of rotation.

'7. A machine for end grinding elongated workpieces comprising a rotary grinder having a grinding surface thereon, a rotary workpiece holder having a periphery thinner than said workpieces mounted for motion of said periphery in close proximity to said grinding surface, said periphery having therein workpiece-holding re cesses open laterally to expose the sides of said workpieces, a rotary driving element engageable with said workpieces on one side of said workpiece holder, and a rotary pressure device having tapered pressure rollers engageable with said workpieces on the opposite side of said workpiece holder to urge said workpieces into driving engagement with said driving element.

8. A machine for end grinding elongated workpieces comprising a rotary grinder having a grinding surface thereon, a rotary workpiece holder having a periphery thinner than said workpieces mounted for motion of said periphery in close proximity to said grinding surface, said periphery having therein workpiece-holding recesses open laterally to expose the sides of said workpieces, a rotary driving element engageable with said workpieces on one side of said workpiece holder, and a rotary pressure device having inwardly-tapered pressure rollers engageable with said workpieces on the opposite side of said workpiece holder to urge said workpieces into driving engagement with said driving element.

9. A machine for end grinding elongated workpieces comprising a rotary grinder having a grinding surface thereon, a rotary workpiece holder having a periphery thinner than said workpieces mounted for motion of said periphery in close proximity to said grinding surface, said periphery having therein workpiece-holding recesses open laterally to expose the sides of said workpieces, a rotary driving element engageable with said workpieces on one side of said workpiece holder, and a rotary pressure device having outwardly-tapered pressure rollers engageable with said workpieces on the opposite side of said workpiece holder to urge said workpieces into driving engagement with said driving element.

10. A machine for end grinding elongated work- 'I6 pieces comprising a rotary grinder having a grinding surface thereon, a rotary workpiece holder having a periphery thinner than said workpieces mounted for motion of said periphery in close proximity to said grinding surface, said periphery having therein workpiece-holding recesses open laterally to expose the sides of said workpieces, a rotary driving element engageable with said workpieces on one side of said workpiece holder, and a rotary pressure device having pressure rollers engageable with said workpieces on the opposite side of said workpiece holder to urge said workpieces into driving engagement with said driving element, certain of said rollers having convexly bulging contact surfaces.

11. A machine for end grinding elongated workpieces compris-ing a rotary grinder having a grinding surface thereon, a rotary workpiece holder having a periphery thinner than said workpieces mounted for motion of said periphery in. close proximity to said grinding-surface, said periphery having therein workpiece-holding recesses open laterally to expose the sides of said workpieces, a rotary driving element engageable with said workpieces on one side of said workpiece holder, and a rotary pressure device having pressure rollers engageable with said workpieces on the opposite side of said workpiece holder to urge said workpieces into driving engagement with said driving element, the axes of rotation of said pressure rollers being directed through a substantially common point of intersection on the axis of rotation of said driving element, certain of said rollers having convexly bulging contact surfaces.

l2. A machine for end grinding .elongated workpieces comprising a rotary grinder having a grinding surface thereon, a rotary workpiece holder having a periphery thinner than said workpieces mounted for motion of said periphery in close proximity to said grinding surface, said periphery having therein workpiece-holding recesses open laterally to expose the sides of said workpieces, a rotary driving element engageable with said workpieces on one side of said workpiece holder, and a rotary pressure device having pressure rollers engageable` with said workpieces on the opposite side of said workpiece holder to urge said workpieces into driving engagement with said driving element, said rollers being mounted in pairs on said device with the rollers of each pair having substantially parallel Aaxes of rotation, certain of said rollers having convexly bulging contact surfaces.

13. A machine for end grinding elongated workpieces comprising a rotary grinder having a grinding surface thereon, a rotary workpiece holder having a periphery thinner than said workpieces mounted for motion of said periphery in close proximity to said grinding surface, said periphery having therein workpiece-holding recesses open laterally to expose the sides of said workpieces, a rotary driving element engageable with said workpieces on one side of said workpiece holder, and a rotary pressure device having pressure rollers engageable with said workpieces on the opposite side of said workpiece holder to urge said workpieces into driving engagement with said driving element, the axes of rotation of said pressure rollers being directed through a substantially common point of intersection on the axis of rotation of said driving element, certain of said rollers ,being resiliently mounted and having convexly bulging contact surfaces.

14.15; machine for end vgrinding elongated workpieces comprising a Arotary grinder `having .a `grinding surfacethereon, a rotary workpiece .holdervhaving a periphery thinner than said piece .holder Ito urge said worlrpieces into driving engagement with `said driving element, said .rollers being vmounted -in pairs on said device with `the rollers or each pair having substantially-parallel axes ofV rotation, certain of said rollers being resiliently mounted andhaving convexly bulging contact surfaces.

115. A machine for end grinding elongated workpieces comprising va rotary grinder having Ia grinding surface thereon, a rotary workpiece holder having a periphery thinner than ysaid Workpieces mounted for motion of said periphery in close proximity to .said grinding surface, said periphery having therein workpiece-holding recesses openlaterally to expose :the sides of said workpieces, a rotary driving element engageahle with said workpieces on one side of said workpiece holder, and Ya vrotary pressure device having pressure rollers engageable with said worklpieces on rthe opposite side of said workpiece holdertonrge said workpieces into driving engagement with said driving element, certain of said rollers being `tapered and others of said rollers'being tresiliently mounted and having convexly bulging contact surfaces.

16. A machine for end grinding elongated workpieces comprising a rotary grinder having a grinding surface thereon, a rotary workpiece holder having a periphery thinner than said wvorkpieces mounted formotion of said periphery in close proximity to said grinding surface,

said periphery having therein'.workpiece-holding recesses open laterally to `,expose the ysides -of said workpieces, a rotary driving elementengageable with said workpieces on 4one side of said workpiece holder, and a rotary pressure device having pressure rollers engageable with said workpieces on the opposite side of Asaid -workpiece holder to urge said workpieces into driving engagement with said driving element, -certain of said rollers vbeing tapered inwardlyand others of said rollers being resiliently mounted and having convexly bulging contact surfaces.

17. -A machine for end grinding elongated workpieces comprising a rotary grinder having vagrinding vsurface thereon, 'a rotary workpiece holder having a periphery/thinner than said workpieces mounted for motion of said periphery -in close proximity to said 'grinding'surfaca said periphery having therein workpiece-holding recesses open laterally to expose the sides of said workpieces, a rotary driving element engageable with said workpieces on one side of said workpiece holder, and arotary :pressure A device having pressure rollers engageahle .with said workpieces on the opposite side of saidworkpiece holder to urge said workpieces -into driving engagement with said `driving element, .certain of said Vrollers being tapered outwardly` and others of said `rollers being resiliently mounted and having convexlybulging contact surfaces.

.GLEN F. JOHNSON.

REFERENCES CITED The following references are :of record in the le of this :patent:

UNITED STATES PATENTS Number yName Date 1,892,363 Raule Dec. 27,41932 1,926,974 Einstein Sept.A 12, 1933 2,024,118 Vanderbeek Dec. 10, 1935 2,109,600 Vanderbeek Mar. 1, 1938 2,434,245 Johnson Jan. .13, 1948 

